Razors, whether of the replacement blade/cartridge type or of the disposable variety include a handle, a blade, a support platform or seat upon which the blade rests, a guard bar which is an extension of the platform beyond the cutting edge of the blade positioned below its cutting edge and a cap which protects the top of the blade and aids positioning. Razor systems are used herein refer to both the disposable and replacement blade/cartridge type.
Guard bars protect the face from deep direct cuts by the blade by extending beyond the cutting edge and also serve to control skin flow to the blade in combination with the blades relative position.
The prior art is replete with a variety of guard bar configurations, for example, U.S. Pat. No. 2,548,959 issued to Eisenberg et al describes a guard bar extension of soft resilient rubber for a double edged blade razor designed to stretch the skin to make the whiskers "pop up." This rather complicated construction requires the addition of L-shaped rubber segments which extend from the metal platform used to support the blade.
U.S. Pat. No. 3,138,865 issued to Meyer describes a guard bar for a double edge blade which extends a substantial distance beyond the blade edge. The blade overlays troughs used for gathering shaving debris positioned adjacent the edge of the guard bar with the guard bars themselves forming a series of toothed serrations extending longitudinally about the guard bar circumference from the top to the bottom with the grooves positioned transversely and parallel to the cutting edge.
U.S. Pat. No. 2,374,612 issued to Mellon describes a razor of the double edged blade type having a serrated cap which extends to an area just short of the blade edge and a single line of squared serrations which extends from the platform to form a guard bar jutting beyond the blade edge. The serrations define slots which extend inward from the blade edge and are designed, according to the inventor, to retain water to aid in the lubrication of the face during shaving.
U.S. Pat. No. 2,817,146 issued to Roberts describes a guard bar with an essentially circular profile for a double edge blade. The guard bar which extends substantially beyond the blade cutting edge provides an essentially circular profile for minimum guard bar contact with the face to prevent pressing facial hair down. This guard bar has a transverse groove which is lightly serrated to accentuate this low friction aspect of the guard bar surface contact.
U.S. Pat. No. 2,568,047 issued to Anderson describes a guard bar for double edge razor which is basically a rotating auger.
U.S. Pat. No. 2,766,521 issued to Benvenuti discloses a guard bar having rotating wheels positioned around the common shaft also for a double edge blade.
U.S. Pat. No. 489,832 describes a double edge blade having a guard bar of rather complicated construction which claims the use of hair raising means with barbed ends which are spring mounted on a flange to prevent stretching of the user's skin.
Martin in U.S. Pat. No. 2,300,794 also discloses a guard bar is with a cylinder in a trough which is rotated by facial contact.
One of the more successful guard bar configurations is disclosed in U.S. Pat. No. 3,722,090 issued to Dawidowicz. This patent discloses a guard bar with a plurality of ridges spaced along the upper surface. Each of the ridges has an articulate outer surface extending from the continuous guard bars surface upwardly and inwardly toward the blade such that the upper portion of the ridges is closely proximate to the cutting edges of the blade. These ridges smooth and stretch the skin prior to the skin coming into a cutting engagement with the blade. According to the disclosure of this patent, this skin between the spaced ridges will bow slightly when taut as a result of the smoothing and stretching action of the upper surfaces of the ridges of the guard bar. This action smoothes and stretches skin imperfections such that a minimum amount of skin enters between the guard bar and the cutting edge, thus minimizing the possibility of nicks and cuts.